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pH and mV Meters
171
  pH and mV Meters
Choosing a pH Meter that’s Right for You!
• The most important part of the pH meter is the electrode. All modern pH meters feature an internal combination electrode. This term indi­ cates that an ion­selective electrode permeable to H+ ions is combined internally with a reference electrode. With a combination electrode the pH meter automatically converts mV measurements to pH values.
• Electrodes are also the most sensitive and fragile element of a pH meter. Gel­filled electrodes require almost no maintenance and are generally more durable, especially for laboratory or field use. Refillable electrodes are more accurate and may have a longer life, but they also require periodic maintenance to refill the electrode body with the appropriate electrolyte solution.
• A pH meter is in essence a very sensitive voltmeter. An instrument­ quality pH meter allows readings of both mV and pH units. This versatility allows the user to check the performance accuracy of the electrode.
• The pH value of a solution depends on temperature. The effect is small (0.003 pH units per degree Celsius). Modern, instrument­ quality pH meters feature automatic temperature compensation, or ATC, which automatically corrects the pH reading for the actual temperature by means of a temperature sensor built into the electrode. Some pH meters also allow manual temperature correction.
Flinn pH Meter Selection Chart
 Catalog No.
  pH Meter Model
  pH Range and Accuracy (±)
  mV Range and Resolution
  Line- or Battery- Operated
  Type of Readout
  Temperature Control
  Combination Electrode
  Price
   AP8673
Flinn
 0.00–14.00 0.1
  NA
Batteries (Four 1.5 V) Furnished
  LCD
NA
 Gel-Filled
  $ 51.10
 AP8901
  Oyster
  0.00–14.00 0.02
  -999–999 1.1
  Battery (9 V) Furnished
  LCD
  Manual or Auto (0–100 °C)
  Gel-Filled
  261.00
   AP7708
Portable pH Meter Kit
 0.00–14.00 0.02
  -499–499 0.1
Battery (4 AAA) Furnished
  LCD
Manual or Auto (-5–80 °C)
 Gel-Filled
  329.50
 AP7452
  pH and Conductivity Meter, Benchtop
  0.00–14.00 0.02
  ±1999.9 0.1
  AC Adapter
  LCD
  Manual or Auto (-5–80 °C)
  Gel-Filled
  451.75
   AP9701
Flinn Desktop Digital pH Meter
 0.00–14.00 0.02
  0±1999 1.0
AC Adapter
  LED
Automatic (0–100 °C)
 Refillable
  519.45
 AP9702
 Flinn Benchtop Touchscreen pH Meter
 -2.00–19.00 0.002
 -1999–1999 0.1
 AC Adapter
 LCD Touch-Screen
 Automatic (0–100 °C)
 Refillable
 661.45
 AP7633
  Advanced pH Meter Kit, Benchtop, Orion StarTM
  -2.00–16.00 0.1, 0.01
  ±1999.9
  AC Adapter (or 4 AA Batteries)
  LCD
  Automatic (-5–105 °C)
  Refillable
  910.70
    See free How to Store, Maintain and Calibrate pH Electrodes video at flinnsci.com.
 pH Meters $5110 Affordable and
 Flinn pH Meter
• Large easy­to­read display
• Replaceable electrode
• Slim design easily fits into test tubes and can be immersed to 80 mm
• Four 1.5 V batteries included; replacement batteries listed below.
• Store the electrode with a few drops of pH 7 buffer or tap water. Never
use deionized or distilled water and never store dry.
• Upon receipt, pH meters must be removed from packaging and stored according to included instrucitons.
Specifications:
Range: 0.00–14.00 pH Resolution: 0.01 pH Accuracy: Better than ±0.1 pH Calibration: 1 point
Battery Life (4 x 1.5 V): 3,000 hours Dimensions: 171 x 51 x 25 mm
Flinn pH Calibration Kit
Keep your Flinn pH meter readings accurate with
the Flinn pH calibration kit. Kit includes 100­mL
bottles of pH 4 and pH 7 solutions, calibration screwdriver, and instructions.
Compact!
Flinn pH Meter AP8673
                   Catalog No.
 Description
 Price/Each
  Price/Each Quantity 3–5
  Price/Each Quantity 6–11
  Price/Each Quantity 12 or more
 AP8673
  Flinn pH Meter
  $51.10
   $50.10
   $49.14
   $48.27
   AP7215
Replacement Electrode
   21.80
  21.57
  21.36
  21.15
 AP8714
 Replacement Battery, 1.5 V (three required)
  3.45
 Flinn pH Calibration Kit AP8720
                 pH Meter Accuracy
The accuracy of pH meters depends on the accuracy of the buffer solutions used for calibration. For greatest accuracy, use only fresh and accurately prepared buffer solutions when calibrating your pH meter.
 Catalog No.
  Description
  Price/Each
   AP8720
 Flinn pH Calibration Kit
   $14.60
 pH METERS continued on next page.
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